Why do you think this concept is limiting? It merely provides some sensible, percentage target options for when trying to build a point - nobody has said (as far as I am aware) that the targets outlined are the only shots available. I've used a similar concept with some of our wheelchair players to good effect - it provides a good building block to use to create opportunities.

Cheers

Exactly, it is a reference or a guide. It can definitely help develop good hitting patterns that can be effective and also consistent.